"This happened as a result of someone else's actions on this child," Grabenstetter said.

Grabenstetter said the cause of death was hyperthermia -- or overheating. The baby's temperature had reached 108 degrees when he was pronounced dead July 29 in the emergency room of Medina General Hospital.

Todd Costello has said he forgot his son was in the back seat when he went in to his job at a packaging business that morning. A co-worker discovered the baby about three hours later in the locked car.

David McArtor, Costello's lawyer, said the death was accidental.

"To anyone who knows Todd Costello it is apparent that this is nothing more than an absolute, tragic, tragic accident," he said.